Circuit controlling device



Jan. 22, 1935. c. w. MN 1 ,988,

- C IRGUIT CONTROLLING DEVICE Filed Feb. 9, 1931 s snets-Sneet 17 f a gs 1 2s 14z 14zk 1a4---- /-1zr 109 a 445 f g -105 I N 141 147 145 10aJan. 22, 1935. c. w. KUHN CIRCUIT CONTROLLING DEVICE Filed Feb. 9, 19313 Sheets-Sheet 2 w .4 51 19 zo a'w 51 I 4?.

Jan. 22, 1935. c. w. kuHN 1,988,848

CIRCUIT CONTROLLING DEVICE Filed Feb. 9, 1951 5 Sheets-Sheet 3 paw 10Vflgwio if 184 L. Q7 1% Patented Jan. 22, 1935 omcurr oouraoLmvo DEVICEClarence W. Kuhn, Milwaukee, Wis., assignor to Cutler-Hammer, Inc.,Milwaukee, Wis., a corporation of Delaware Application February 9, 1931,Serial No. 514,363

22 Claims.

6 of the household type.

In refrigerators of the household type refrigeration is usuallyaccomplished by a compressor driven by an electric motor and automaticmeans is usually provided for starting and stopping the motor tomaintain the temperature within the refrigerator between selectedvalues. Also such refrigerators are usually provided with overloadprotective means for automatically interrupting the motor circuit if,the motor .becomes stalled or overloaded and with. manually controlledmeans for'rendering the motor inoperative to effect what is known asdefrosting.

It has heretofore been proposed to aggregate in a single unit theseveral elements necessary to effect control of electric refrigeratorsin the manner above set forth. However, as heretofore constructed suchunits were provided with separate manual adjustments for varying thetemperature values at which the refrigerator motor is started andstopped, for resetting the overload protective means and for renderingthe motor inoperative to provide for defrosting.

The present invention has among its objects to provide an improvedcontrol unit for electric refrigerators including a single controlelement which is adjustable to vary the temperature values at which themotor is started and stopped and which is also adjustable to reset theover- ,load means and to effect stopping of the motor for defrosting.

Another object is to provide a refrigerator controller of the aforesaidcharacter consisting of control parts which can be assembled in variousrelations with respect to each other to suit the space conditions withinthe refrigerator.

Another object is to provide an improved refrigerator controller of theaforesaid character having its parts arranged whereby the same arereadily accessible for inspection or repair.

Another object is to provide a refrigerator controller having animproved temperature responsive device associated therewith which can bereadily adjusted to maintain the temperature within the refrigeratorbetween selected values. Another object is to provide a refrigeratorcontroller including a single switch which is. adapted to be openedautomatically to protect the refrigerator motor against overloads, andwhich is also adapted to be controlled manually to stop said motor fordefrosting.

Various other objects and advantages of the inventio will hereinafterappear.

The accompanying drawings illustrate an embodiment of the inventionwhich will now be described, it being understood that the embodimentillustrated is susceptible of modification without departing from thespirit and scope of the appended claims.

In the drawings,

Figure 1 is a side elevational view partly in section, of a refrigeratorhaving a control device embodying the invention associated therewith;

Fig. 2 is a side elevational view of a control device embodying theinvention, the enclosing cover being shown in section;

Fig. 3 is a front view of the control device shown in Fig. 2;

Fig. 4 is a sectional view of a temperature responsive switch shown inFigs. 2 and 3;

Fig. 5 is a fragmentary sectional view similar to that shown in'Fig. 4,illustrating certain of the switch parts in another position;

Fig. 6 is a perspective view of a bracket and a lever shown in Fig. 4;

Fig. 7 is a sectional view on line 7-'7 of Fig. 4;

Fig. 8 is a sectional view on line 8-8 of Fig. 4;

Fig. 9 is a rear elevational view of a combined overload and defrostingswitch shown in Figs. 2 and 3;

Fig. 10 is a view similar to Fig. 9 illustrating the switch in anotherposition;

Fig. 11 is a sectional view on line 1111 of Fig. 9;

Fig. 12 is a sectional view of a starting relay shown in Fig. 2;

Figs. 13 and 14 are plan views of the relay shown in Fig. .12illustrating different contact and terminalarrangements for such relay;

Fig. 15 is a sectional view on line l5--15 of Fig. 14, and

Figs. 16 and 17 are diagrammatic views illustrating different circuitarrangements for the control device.

Referring to Fig. l, the same illustrates arrefrigerator comprising acasing 1 having a machine compartment 2 in the lower part thereof whichcontains a motor driven compressor 3 and having a cooling compartment 4in the upper part thereof which contains an expansion unit 5. Expansionunit 5 and compressor unit 3 are connected in the usual manner by highand low pressure pipes for circulation of a refrigerant, and in theembodiment illustrated said compressor unit is controlled by a unit 6mounted within a ventilating duct 7 located at the rear of casing 1 andextending upwardly from the machine compartment 2.

'As shown in Figs. 2 and 3, control unit 6 includes a temperatureresponsive device 8, an electroresponsive starting relay 9 and anelectrothermal overload device 10. As hereinafter set forth device 8 isadapted to start and stop the driving motor upon predeterminedtemperature values within the refrigerator and the same is adjustable bya knob 11 (Fig. 1) to vary the temperature values at which the motor isstarted and stopped. Also as hereinafter set forth the overload device10 is adapted to be reset by knob 11 and is operable by said knob tostop the driving motor for defrosting.

The construction and operation of the above mentioned control elementswill now be more fully described.

The temperature responsive device 8 is provided with a switch 13 forcontrolling the line connections of the driving motor. Said switch isprovided with a pivoted operating lever 14 which is under the control ofa temperature responsive element of the well known sylphon typecomprising a bellows 15 which. is connected to a closed pipe extension16 to be arranged within the cooling compartment of the refrigerator.Pipe extension 16 contains a fluid, as for example methyl chloride andupon temperature changes within the cooling compartment the temperatureof the fluid within said extension varies to effect expansion andcontraction of bellows 15. Upon an increase in temperature within thecooling compartment bellows 15 expands and moves operating lever 14outwardly against the action of an associated spring 17 (Fig. 4) .andupon a predetermined maximum temperature value said lever moves into aposi tion wherein the same effects closure of switch 13 to start thedriving motor. Upon a decrease in temperature within the coolingcompartment bellows 15 contracts to permit inward movement of lever 14under the action of spring 17 and upon a predetermined minimumtemperature value said lever moves into a position wherein the sameeffects opening of switch 13 to stop the driving motor.

In connection with the foregoing it should be noted that since thepressure within the refrigerator system varies in accordance with thetemperature values, switch 13 can be controlled in the required mannerby subjecting bellows 15 to pressure variations As shown in Fig. 4bellows 15 is secured at its inner end by a nut 18 within an openingpro-. vided in an inverted L-shaped bracket 19 and the outer end of saidbellows seats within a suitably formed recess in the inner face of lever14. The upper end of lever 14 is provided with an inwardly extendingprojection 20 and as shown in Fig. 6 the inner end of said projection isprovided with a T-shaped tongue 21 adapted to be inserted into anopening 22 in bracket 19 to pivotally secure said lever to said bracket.As shown in Fig. 6 tongue 21 is adapted to interlock with shoulders23--23 formed on the lower edge of opening 22 in bracket 19 and thelower edge of said opening is shaped to provide a knife edge bearing 24for engaging the under side of the neck portion of said tongue as shownin Fig. 4. Also as shown in Fig. 6 the inner end of projection 20orflever 14 is shaped to provide knife edge bearings ,25-25 for engagingthe front face of bracket 19 on opposite sides of opening 22. The lowerend of lever 14 is provided with an inwardly extending projection 26having a forked portion 27 on the end thereof for receiving a downwardlyextending projection 28'on the lower end of bracket 19. As shown in Fig.6 the forked portion 27 of lever 14 is shaped to provide shoulders 29-29and 30-30 for engaging the front and rear faces of projection 28 onbracket 19 to limit pivotal movement of said lever in oppositedirections.

As hereinbefore stated lever 14 has a spring 17 associated therewithwhich opposes outward movement thereof by bellows 15. Spring 17 isarranged between lever 14 and bracket 19 and is held under compressionbetween a U-shaped stirrup 31 fixed to said lever and a nut 32associated with a screw 33. Stirrup 31 is arranged within an opening 34in lever 14 (Fig. 6) and the same is provided with outwardly bentportions on the extremities thereof which are secured to the front faceof said lever by welding. Nut 32 is arranged between a pair of washers35-36 which are clamped to said nut by a screw 37 and as shown in Figs.2 and 4 said washers are provided with projections 38 and 39 whichextend upwardly into a recess 40 in the upper leg of bracket 19 to fixsaid nut against rotation. Screw 33 extendsthrough an opening in bracket19 and has an enlarged head 42 on the inner end thereof which abuts therear face of said bracket. The head 42 of said screw is adapted to becoupled by a suitable shaft to the adjusting knob 11 shown in Fig. 2 andas is apparent said screw is thus rotatable by said knob to move nut 32inwardly or outwardly for variation of the degree of compression ofspring 17.

As shown in Fig. 8 the switch 13 of the device is provided with aninsulating base 45 which is secured to bracket 19 by screws 46. A pairof terminal plates 47 and 48 are secured to the front face of said baseand the former plate has a spring contact 49 associated therewith whichis biased to engage the latter plate. Spring contact 49 is provided withan operating pin 50 which is formed of insulating material and isslidably mounted within an opening in base 45. The inner end of said pinextends into a recess 51 in the rear face of insulating base 45 and saidrecess contains a snap operating mechanism which is associated with theactuating lever 14.

The snap operating mechanism includes an inverted U-shaped plate 52, thelegs of which are provided with knife edge ends which seat withinrecesses 53 (Fig. 5) formed in the upper face of the forked portion 27of lever 14. The upper end of plate 52 is connected by a tension spring54 to a pin 55 which is located immediately below the lower end of lever14 and is secured within an opening in bracket 19 by a nut 56. Outwardmovement of the upper end of plate 52 is limited by engagement thereofwith the face of recess 51 in base 45 and inward movement of the upperend of said plate is limited by engagement thereof with a screw 57 whichis threaded within an opening in bracket 19. Forv a purpose hereinafterset forth screw 57 is adjustable with respect to bracket 19 and tofacilitate adjustment thereof the same is provided with a recess 58 forreceivinga' suitable adjusting tool which can be inserted into saidanopening for receiving said screw and the lower end of which is fixed tobracket 19 by the nut 56 associated with pin 55.

The operation of the aforedescribed device will now be more fully setforth. When operating lever 14 is moved to a position wherein thepivotal axis of plate 52 is located to the left of the axis of spring 54plate 52 is held in the position shown in Fig. 5. With plate 52 in thisposition the pin 50 isheld in a projected position to maintain springcontact 49 of switch 13 out of engagement with terminal plate 48. Ashereinbefore stated switch 13 controls the line connections for thedriving motor and when the parts assume the position shown in Fig. 5 thedriving motor is stopped. When the driving motor is stopped thetemperature within the refrigerator tends to increase and when such tenperature increases to a selected value determined by the degree ofcompression of spring 17, bellows 15 moves lever 14 outwardly againstthe action of said spring into a position wherein the pivotal axis ofplate 52 is located to the right of the axis of spring 54. Plate 52 isthen moved with a snap action by spring 54 from the position shown inFig. 5 to the position shown in Fig. 4 and permits spring contact 49 tomove into engagement with terminal plate 48 to start the driving motorof the refrigerator. The temperature Within the refrigerator thendecreases and upon a predetermined temperature drop within therefrigerator bellows 15 permits lever 14 to move inwardly under theaction of spring 17 into a position wherein the pivotal axis of plate 52is located to the left of the axis of spring 54. Plate 52 is then movedwith a snap action by spring 54 from the position shown in Fig. 4 intothe position shown in Fig. 5 and opens the spring contact 49 of switch13 to stop the driving motor.

As hereinbefore stated the temperature value at which the driving motoris started is determined by the degree of compression of spring 17, andas is apparent such temperature can be increased or decreased as desiredby adjustment of screw 33. The device is also adjustable by screw 57 toprovide for variation of the range of temperature drop which is requiredto effect stopping of the driving motor. As is apparent, adjustment ofscrew 57 outwardly advances the point at which switch 13 is openedduring'movement of lever 14 inwardly from the position shown in Fig. 4to thereby decrease the range of temperature drop required to eilectstopping of the driving motor, while inward adjustment of said screw hasa reverse effect.

Starting relay 9 is provided with a spring contact 65 arranged upon theupper face of an insulating plate 66 and having its inner end secured tosaid plate between insulating bushings 67 and 68 by a bolt 69. Plate 66is mounted upon a C-shaped bracket 70 by screws 71? and said platecarries a solenoid having an operating winding 73 fixed to the lowerface of said plate and a plunger 74 operativelyconnected to the outerend of spring contact 65.

Winding 73 is wound upon an insulating spool 75 having a cenQ'al openingtherein for receiving plunger 74, and said spool is secured to amagnetic washer 76 which is fixed to the under face of insulating plate66 by screws 77 shown in Fig. 13. Insulating spool 75 is secured towasher 76 by a magnetic plug 78 which is threaded into said washer andis provided with an enlarged head for engaging a shoulder provided onthe upper end of said spool within the opening therein. The lower end ofplunger 74 is weighted by a flange portion 79 and said plunger has aninsulating pin 80 mounted upon the upper end thereof which is slidablewithin an opening in plug 78. The outer end of spring contact 65 isprovided with an opening for receiving pin 80 and said pin has aninsulating washer 81 mounted upon the upper end thereof for engaging theupper face of said spring contact.

Spring contact 65 is normally held in the position shown in Fig. 12 byplunger 74 and is biased to move upwardly from such position upon upwardmovement of said plunger into its attracted position. To prevent hummingof the plunger when the same is moved into its attracted position arubber washer 82 is mounted upon the upper face of flange 79. Saidwasher is adapted to engage the lower face of spool 75 to preventsealing of the upper end of plunger 74 with plug 78. A plurality ofrelatively thin fabric shims are interposed between washer 82 and theupper face of flange 79, and as is apparent, by varying the number ofshims employed the air gap which is maintained between the upper end ofplunger 74 and plug 78 may be adjusted to provide for dropping out ofthe plunger at a selected current value in winding 73. To provide forvariation of the current value at which plunger 74 is adapted to moveinto its attracted position a shim adjustment 81 is associated withwasher 81 which provides for adjustment of the normal position of saidplunger'with respect to plug 78. 4

The above described relay is designed so that the same can be used toprovide suitable connections for different starting arrangements. Forone starting arrangement a resistance element 83 is secured to bracket70 by a bolt 84 and plate 66 is provided with a contact and terminalarrangement shown in Fig. 13. For another starting arrangement theresistance element is omitted and plate 66 is provided with a contactand terminal arrangement shown in Figs. 14 and 15.

In Figs. 13 and 14 plate 66 has a stationary contact 85 fixed to theupper face thereof which is adapted to be engaged by spring contact 65upon upward movement thereof from the normal position shown in Fig. 12,and in Fig. 14 an additional stationary contact 86 is mounted upon theupper face of plate 66 which is adapted to be engaged by spring contact65 when the latter is in normal position as shown-in Fig. 15. In Fig. 13plate 66 has a plurality of terminal plates 87, 88 and '89 mounted uponthe upper face thereof. Terminal plate 87 is electrically connected tothe inner end of spring contact65, resistance unit. 82 is connectedbetween terminal plates 87 and 88, and the operating winding 73 of therelay is connected between stationary contact 85 and terminal plate 89.In Fig. 14 the insulating plate 66 has terminal plates 90 and 91 mountedupon the upper face thereof and the former plate is electricallyconnected to the inner end of spring contact 65 while the operatingwinding 73 of the relay is connected between terminal plates 90 and 91.In connection with the foregoing it should be noted that insulatingwithin a recess 96 provided in the rear face of an insulating base 97.Said switch has an electrothermally controlled tripping mechanism 98asswitch without tripping of said mechanism. 10

Switch is provided with a spring contact 99 having its upper end fixedto an L-shaped supporting member 100 and having its lower end biased toengage an L-shaped contact member 101. Members 100 and 101 are securedto the rear face of insulating base 97 by screws 102 and 103,respectively, and said screws pass through openings in said base and arethreaded into terminal plates 104 and 105, respectively, mounted uponthe front face of said base as shown in Fig. 3.

The electrothermally controlled tripping mechanism 98 includes anelectrothermal device 106, a pawl 107 associated with said device and aswitch operating lever 108 carried by said pawl. As shown in Fig. 11electrothermal device 106 includes an electric heater 109 of helicalform mounted within a recess 110 in the front face of insulating base97; a tubular member 111 fixed within an opening in said base and havingits outer end surrounded by said heater and a ratchet pin 112 locatedwithin said tubular member. The outer end'of ratchet pin 112 isconnected to tubular member 111 by a soldered connection 113 and theinner end of said pin is provided with an enlarged toothed head 114 tobe engaged by pawl 107.

Pawl 107 is slidably mounted upon the rear face of insulating base 97within recess 96 and the same has a tooth projection 115 intermediatethe, ends thereof for engaging the head 114 of L the ratchet pin. Saidpawl and also the ratchet pin 112 are held in position upon insulatingbase 97 by a plate 116 secured to said base by a screw 117. The lowerend of said pawl is provided with a slot 'for receiving a projection 119upon the rear face of insulating base 97, and the upper end of said pawlis connected to plate 116 by a spring 120. Spring 120 biases pawl 107downwardly from the position shown in Fig. 9 and also biases the upperend thereof towards the left to hold the tooth projection 115 thereon inengagement with head 114 of the ratchet pin.

Lever- 108 is formed of insulating material and is pivotally securedintermediate its ends to the lower end of pawl 107 by a pin 121. Asshown in Fig. 9 the left hand end of said lever is provided with a camsurface 122 for engaging spring contact 99, and is also provided with a,shoulder 123 for engaging the upper edge of stationary contact 101. Theright hand end of said lever projects outwardly through an opening 124in the wall to the right of recess 96, and as shown in Fig. 9 the face125 at the lower end of said opening provides a stop for engaging theunder side of said lever. v

As hereinbefore set forth, spring contact 99 and stationary contact 101are respectively connected to terminal plates 104 and 105 mounted uponthe front .face of insulating base 97. As shown in Fig. 3 the front faceof said insulatingv base also has a terminal plate 126 mounted thereonand one terminal of the electric heater 109 is connected to said platewhile the opposite terminal thereof is connected to terminal plate 105.Also as shown in Figs. 2 and 3 the front face of insulating base 97 hasa pair of projecting contact prongs 127 and 127 mounted thereon, theformer prong being connected to terminal plate 126 by a connection 128.

The function and operation of the aforedescribed overload and defrostingswitch will now be more fully described. The contact prongs 127 and 127are adapted to be plugged into a suitable receptacle having contactsconnected to the supply circuit of the refrigerator, and as hereinafterset forth current is-supplied to the driving "motor through switch 95and heater coil 109. Normally pawl 107 and operating lever 108 are inthe positions shown in full lines in Fig. 9 and upon rotation of saidlever from its full line position into its dotted line position the cam.surface 122 thereon moves spring contact 99 out of engagement withstationary contact 101. The driving motor is thus rendered inoperativeto provide for defrosting of the refrigerator and after defrosting lever108 is returned t3 its full line position to permit reclosure of springcontact 99.

If the driving motor becomes stalled or overloaded, heater coil 109serves to fuse the solder connection 113 of device 106 and the ratchetpin 112 is then released to permit rotation thereof within the tubularmember 111. Upon release of said ratchet pin pawl 107 moves downwardlyunder the action of spring 120 from the normal position illustrated inFig. 9 to the full line position illustrated in Fig. 10. Upon downwardmovement of pawl 107 into the full line position illustrated in Fig. 10lever 108 assumes the position shown in full lines in this figure andthe cam surface 122 thereon moves spring contact 99 out of engagementwith stationary contact 101 to interrupt the motor circuit. Upontripping of pawl l07'the shoulder 123 on lever 108 rests upon the upperedge of stationary con tact 101 and said lever is then adapted upon up-Ward movement of the right hand end thereof from the position shown infull lines in Fig. 10 to the dotted line position illustrated in thisfigure to reset said pawl in the position shown in full lines in Fig. 9.It should be noted that during resetting operation spring contact 99 isheld in open position by lever 125.

Lever 108 is normally held in the position shown in full lines in Fig. 9by a weighted link 130 which is suspended within an opening in the righthand end of said lever. The lower end of said link is adapted to beengaged by a pin 131 which is fixed to the head 42 of adjusting screw 33associated with the temperature responsive device 8. As is apparent fromFig. 4 pin 131 is adapted to engage the T-shaped tongue 21 on operatinglever 14 ofv the temperature responsive device to limit rotation of saidscrew in opposite directions between the extreme positions illustratedby full and dotted lines in Fig. 9. During rotation of screw 33 into theextreme position illustrated in dotted lines in Fig. 9 pin 131 engagesthe lower end of link 130 to mpve the same upwardly. Upon movement ofpin 131 into the defrosting position illustrated by dotted lines in Fig.9 lever 108 effects opening of switch 95 for defrosting of therefrigerator, andupon movement of said pin into-the reset positionillustrated by dotted lines in Fig. 9 lever 108 is moved into its resetposition. Screw 33 of the temperature responsive device is preferablyprovided with a left hand thread. Thus adjustment of said screw in aclockwise direction (Fig. 9) decreases the degree of compression ofspring 17 to decrease the temperature value within the refrigerator atwhich the driving motor is started, while adjustment of said screw in acounterclockwise direction has a reverse effect.

Referring now to Fig. 16, the above described control unit is shownconnected to control the circuit of a single "phase alternating currentmotor M having a starting winding 135 and a nected to stationary contact85 of the starting,

1 relay and said relay is provided with the termi switch to stop furtherrefrigerating action.

When the temperature within the refrigerator increases to a given valuethe temperature responsive switch 13 closes and circuit for the runningwinding 136 is established extending from line IF through heater coil109 and switch 95 of the overload and defrosting device to and throughthe switch 13 of temperature responsive device 8 to stationary contact85 of the starting relay 9 and thence through the operating winding 73of saidrelay and the running winding 136 of the motor to line L Theinrush of current to the motor immediately causes the winding 73 of thestarting relay to effect movement of spring contact 65 into engagementwith stationary contact 85 and the starting winding 135 is thenenergizedby a circuit extending from line L to stationary contact 85 as alreadytraced, through spring contact 65, through resistance element 83, andthence through the starting winding 135 to line L. When the motor hasstarted the refrigerator compressor and has accelerated to apredetermined speed the current in the operating winding 73 of thestarting relay decreases in value sufficiently to permit return ofspring contact 65 to normal position. This opens the circuit of thestarting winding 135 and the running winding 136 continues operation of.the motor.

As the motor M continues to operate the temperature within therefrigerator is lowered and when the temperature has been lowered to aselected value determined by the setting of the temperature responsiveswitch 8 said switch opens to interrupt the circuit of the drivingmotor. Under normal operating conditions the starting and running cycleof the refrigerator is controlled in the manner just described entirelyautomatically by the temperature responsive switch 8 so as to maintainthe temperature of the refrigerator within the desired limits, saidlimits being adjustable, as hereinbefore set forth, by the knob 11 shownin Fig. 1. Also as hereinbefore set forth the switch 95 of the overloadand defrosting device 10 is adapted to protect the motor againstoverloads and the knob 11 shown in Fig. 1 is operable to reset saidswitch upon tripping thereof, and is also operable to open the same tostop the motor for the medium of an autotransformer winding 137 and acondenser 138, said transformer winding being connected in series withthe starting winding 135 ofthe motor, and said condenser being connectedin shunt with said autotransformer winding. The left hand terminals ofstarting winding 135 and running winding 136 of the motor arepermanently connected to contact prong 127 which is connected to line Land upon closure of switch 13 of the temperature responsive devicecircuit is established from line L through heater coil 109 and switch 95of the overload and defrosting devicethrough switch 13 to terminal plate90 through the operating winding 73 of starting relay 9 to theright handterminal of the running winding 136. The inrush of current to the motorimmediately causes the winding 73 of the starting relay to effectmovement of spring contact 65 into engagement with stationary contact 85and line L is then connected to terminal T of the autotransformerwinding 137. The motor is then adapted to accelerate and when the samehas attained a predetermined speed the current in coil 73 of thestarting relay is reduced to a value to permit return of springcontact65 into engagement with stationary contact 86. This disconnects line Lfrom terminal T of the autotransformer winding and connects such line toterminal T of said transformer winding for running.

In the control unit illustrated the control elements are arranged in avertical relation, the overload and defrosting switch being arrangedabove the temperature responsive switch 8 and the starting relay 9 beingarranged below the latter switch. As shown in Fig. 2 the supportingbracket 19 of temperature responsive switch 8 is fixed to an L-shapedbracket 140 by screws 141 and the latter bracket is secured by weldingto a base member 142 having forwardly extending projections on the upperand lower ends thereof. The insulating base 97 of the overload anddefrosting switch is fixed to the face of bracket 140 by screws 143 andthe lower leg of the bracket 70 of the starting relay 9 is fixed to theforwardly extending projection on the lower end of base 142 by screws145. A box-shaped enclosing cover 146 is carried by base 142, said coverbeing provided with an opening 147 for receiving a receptacle to beplugged on to the prongs 127 and 127' of the overload and defrostingswitch. As is apparent the control elements 8, 9 and 10 can be arrangedin relations other than that shown in Figs. '2 and 3 to suit the spaceconditions within the refrigerator. i

What I claim as new and desire to secure by Letters Patent is:

1. In a circuit controlling device, in combination, a pair of seriesconnected switches for controlling the circuit, one of said switchesbeing responsive to interrupt and establish said circuit in accordancewith predetermined temperature variations in an ambient medium, and theother being responsive upon predetermined overload conditions in saidcircuit to interrupt'the same, and means including a single controlelement operable to vary the temperature values at which said firstmentioned switch opens and closes said circuit, and also operable toopen and close said second mentioned switch at will and to reset thesame in closed position upon response thereof.

2. In a controller for electric refrigerators, the combination with atemperature responsive device for controlling the power circuit of therefrigerator to start and stop the refrigerator upon predeterminedtemperature conditions therein, said device having adjusting meansassociated therewith for varying the temperature values at which thesame effects starting and stopping of the refrigerator, and a cut-outdevice sepa rate from the former device responsive to interrupt thepower circuit of the refrigerator upon given overload conditions in suchcircuit,

said adjusting means being operable to reset said cut-out device uponresponse thereof and being also operable to open and close said outoutdevice at will.

3. In a controller for electric refrigerators, the combination with atemperature responsive device for interrupting and establishing thepower circuit of the refrigerator upon predetermined temperatureconditions within the refrigerator, a cut-out device responsive tointerrupt said power circuit upon given overload conditions therein, andmeans associated with said devices including a single manuallyadjustable part movable in opposite directions between given extremepositions to vary the temperatures at which said temperature responsivedevice establishes and interrupts the power circuit of the refrigerator,said part being also movable within a fractional part of its range intoand out of one extreme position to open and close said cut-out device atwill and to reset the same upon response thereof.

4. In a controller for electric-refrigerators, in combination a switchfor controlling the power circuit of the refrigerator, said switch beingbiased to closed'position, a member operable to open and close saidswitch at will, and an electro-thermallycontrolled tripping mechanismassociated with said member responsive to open said switch uponpredetermined overload conditions in said power 'circuit, said memberbeing operable to reset said tripping mechanism and to efiect theaforementioned opening of said switch while said tripping mechanismremains set.

5. In a controller for electric refrigerators, in

- combination, circuit controlling contacts, adjustable power means foreffecting cyclic operation of certain of said contacts in response tovariations in temperature, thermal overload means for effectingoperation of certain of said contacts, said thermal overload meansincluding a thermal element of the solder-type and an elementnormallyengaged therewitlt' to be restrained thereby, and manual means to effectadjustment of said power means, resetting-of said overload meansfollowing response thereof and setting of certain of said-contacts atwill for defrosting while the aforementioned parts 'of said overloadmeans remain engaged, said manual means including a manually operableelement and means providing for the aforementioned resetting of saidoverload means and also for the aforementioned defrosting setting ofcontacts by adjustments of said manually operable element.

6. In a controller for electric refrigerators, in combination, atemperature responsive device having; contacts for controlling the powercircuit of the refrigerator in accordance with temperature conditionswithin the refrigerator, said device having a manual'adjusting elementassociated therewith for varying the temperatures at which the sameopens and closes said circuit, a normally closed switch for controllingsaid power circuit and electrothermally controlled tripping mechanismassociated with said switch responsive to open the same upon givenoverload conditions in said power circuit, said tripping mechanismincluding a part normally operable to open and close said switch atwill, and also-operable to effect resetting of said tripping mechanismupon response thereof, said part being so operable by the adjustingelement of said temperature responsive device.

7. In a controller for electric refrigerators, the combination with anormally closed switch for controlling the power circuit of therefrigerator, of an element manually operable to open and close saidswitch at will and to retain it open for defrosting, and electro-thermaltripping mechanism of the solder type associated with said element andresponsive to open said switch upon predetermined overload conditions insaid power circuit, said element being operable to reset said trippingmechanism and tomaintain said switch in open position during resettingof said tripping mechanism.

8. In a control device for electric refrigerators, in combination, apair of series connected switches for controlling the power circuit ofthe refrigerator; one of said switches having pressure responsiveoperating means associated therewith and the other being responsive uponpredetermined overload conditions in said circuit to interrupt the same,and means including a single control element operable to vary thepressure values at which said first mentioned switch opens and closessaid circuit and also operable to open and close said second mentionedswitch at will and to resetthe same in closed position upon responsethereof.

9. The combination with a control structure having pressure responsiveactuating means, a

thermal cutout device and an adjustment con-- trol device, of a unitcontrol comprising a knob for actuating the adjustment control device,'said knob being'operatively connected with the thermal cutout device toreset the same follow? ing response thereof, andsaid knob affording theaforestated dual control upon movement thereof in a single plane.

10. In a controller for electric refrigerators, in combination, circuitcontrolling contacts, adjustable power means for effecting cyclicoperation of certain of said contacts in response to variations intemperature, thermal overload means for effecting operation of certainof said contacts, a manual element and means which afford by movement ofsaid element to different positions a low temperature adjustment, adefrosting adjustment and resetting of said,thermal overload means afterresponse thereof the defrosting and resetting positions of said elementbeing adjacent.

11. In a controller for electric refrigerators, in combination, circuitcontrolling contacts, adjustable 'power means for. effecting. cyclicoperation of certain of said contacts in response to variations intemperature, thermal overload means having normally engaged partsdisengageable on overload for effecting operation of certain of saidcontacts, a manual element and means which afford by movement of saidelement to different positions adjustment ofetheaforementioned cyclicoperation, resetting of said thermal overload means after responsethereof and opening of circuit by said contacts at will while said partsof said overload means remain engaged.

12. In a controller for electric refrigerators, in

combination, circuit controlling contacts, ad-

justable power means for effecting cyclic operation of certain of saidcontacts in response to variations in temperature, thermal overloadmeans for effecting operation of certain of said contacts, a manualelement and means which afford by movement of said element to differentpositions a low temperature adjustment, a defrosting adjustment andresetting of said thermal overload means with retention of certain ofsaid contacts in open position during resetting of said thermal overloadmeans.

13. In a controller for electric refrigerators, in combination, circuitcontrolling contacts, adjustable power means for operating certain ofsaid contacts cyclicly in response to temperature variations, thermaloverload means for effecting operation of certain of said contacts, amanual element and means affording by movement of said element to agiven position a certain adjustment'ofthe aforementioned cyclicoperation}.

to another given position circuit interruption by said contacts whilethat part of said overload means sensitive to thermal changes remainsset and to another given position restoration of circuit control to saidpower means and said thermal overload means.

14. In a controller for electric refrigerators, in

combination, circuit controlling contacts, power means for operatingcertain of said contacts cyclicly in response to temperature variations,thermal overload means to effect operation of certain of said contactsto render operation of said power means ineffective for circuit controlpending resetting of said thermal overload means, a manual element andmeans affording by movement of said element while said thermal overloadmeans remains set operation of certain of said contacts at will andresetting of said thermal overload means after response thereof.

15. In a controller for electric refrigerators, in combination, circuitcontrolling contacts, power means for operating certain of said contactscyclicly in response to temperature variations,

- thermal overload means to effect operation of certain of said contactsto render operation of said power means ineffective for circuit controlpending resetting of said thermal overload means, a manual element andmeans affording by movement of said element operation of certain of saidcontacts at will, resetting of said thermal overload means and operationof certain of said contacts to circuit closing position free frominterference with immediate opening thereof if overload occurs uponinitial closure of circuit.

16. In a controller for electric refrigerators, in combination, circuitcontrolling contacts, operating means for certain of said contactscomprising sylphon bellows and an opposing spring continuously activeand alone constituting the major load on saidbellows, a manual devicefor adjusting said spring to vary an operating characteristic of saidmeans and means operable by said manual device to effect defrostingsetting of the controller.

17. In a controller for electric refrigerators, in combination, circuitcontrolling contacts, operating means for certain of said contactscomprising sylphon bellows and an opposing spring continuously activeand alone constituting the major load on said bellows, thermal overloadmeans to effect circuit opening operation of certain of said contacts, amanual element and means affording by adjustments of said manual elementadjustment of said spring to vary an operating characteristic of thefirst mentioned means and resetting of said thermal overload means afterresponse thereof.

18. In a controller for electric refrigerators, in combination, circuitcontrolling contacts, operating means for certain of said contactscomprising sylphon bellows and an opposing spring continuously activeand alone constituting the major load on the bellows, thermal overloadmeans to effect circuit opening of certain of said contacts andassociated external manual means to effect resetting of said thermaloverload means after response thereof and to effect selectively loweringof the refrigerator temperature and defrosting of the refrigerator, saidmanual means comprising a single element to effect such selectivetemperature lowering and defrosting and further comprising means whichenables said element to adjust said spring for accomplishment of certainof its aforerecited functions.

19. In a control system for the motor of an automatic refrigerator, thecombination with a housing, of a temperature responsive mechanismarranged in said housing, means arranged to be operated by saidresponsive mechanism for controlling the circuit of the refrigeratormotor at one point therein, a switch operable to control said circuit atanother point therein, safety mechanism automatically operative when anexcess flow through said circuit occurs to move said switch to open saidcircuit, terminals for said circuit carried by said housing, and manualadjusting means associated with said temperature responsive mechanismand having an element external of said housing by means of which anoperating characteristic of said mechanism may be varied at will.

20. In a control system for the motor of an automatic refrigerator, thecombination with a housing, of a temperature responsive mechanismarranged in said housing, said mechanism including bellows and anopposing spring continuously active and alone constituting the majorload on the bellows, means within said housing arranged to be operatedby said responsive mechanism for controlling the circuit of therefrigerator motor at one point therein, a switch within said housingoperable to control said, circuit at another point therein, safetymechanism within said housing automatically operative when an excessflow through said circuit occurs to move said switch to open saidcircuit, and manual means operable from the to open the latter againstits bias during final movement of said lever into one extreme positionand to permitreclosure of said switch during initial reverse movement ofsaid lever away from such extreme position, an overcenter spring formoving said lever in opposite directions between said extreme positionswith a snap and a fluid condition responsive device acting upon saidspring to effect snap operations of said lever.

.22. In a controller for electric refrigerators, in combination, acontrol switch biased to closed position, a lever movable betweenextreme positions and operativ ely associated withsaid switch to openthe latter against its bias during final movement of said lever into oneextreme position and to permit reclosure of said switch during initialreverse movement of said lever away from such extreme position, anover-center spring for moving said lever in opposite directions betweensaid extreme positions with a snap, a fluid condition responsive elementacting upon said spring to efiect snap operation of said lever, springmeans acting in opposition to said pressure responsive element, a rangeadjusting element for varying the tension of said spring means and adifferential adjusting element associated with said lever for varyingone of the limits thereof.

CLARENCE W. KUHN.

